(1) Field of the Invention
The present invention relates to an electrical power supply device for electrically powering at least one item of equipment on a rotary rotor.
(2) Description of Related Art
The invention lies within the technical field of electrical power supply means for supplying electrical power to a rotary member, and more particularly for electrically powering de-icing/anti-icing members on a rotorcraft rotor.
Some aircraft are equipped with devices for de-icing/anti-icing airfoil surfaces, and in particular surfaces of the blades of a rotor. The problem of icing of such airfoil surfaces is well known in the aeronautical industry, it being possible for the aerodynamic profile of such surfaces to be adversely altered due to ice forming in flight after colliding with supercooled water droplets contained in the atmosphere.
This problem is often dealt with by equipping the airfoil surface with a heater structure.
However, it can be understood that it can be difficult for equipment present on a rotary assembly to be electrically powered from an electricity generator present in a static frame of reference within the airframe of an aircraft.
Various devices are known for conveying electricity to a rotary assembly mounted permanently and irreversibly on propellers, in particular on airscrews or on wind turbine rotor blade assemblies.
Document FR 2 553 596 describes a propeller including electrical energy generator means inside its hub for the purpose of powering an electrical system for altering the pitch of the blades of the propeller, and for the purpose of powering de-icing means.
Document EP 0 629 318 describes the use of a magnet mounted to rotate freely between two coil assemblies arranged inside a propeller.
Document EP 0 777 602 discloses a generator having coils carried by a rotor, those coils co-operating with a static permanent magnet.
Document EP 2 218 643 presents an electrical machine disposed inside a propeller for electrically powering resistance elements. The alternator comprises a stator secured to a static casing of the propeller, and coils secured to a rotary shaft of the propeller.
Document US 2011/0024567 describes electricity-generating apparatus arranged inside a contra-rotating two-airscrew turbo-prop system.
The same applies to Document GB 584 563.
Document WO 2010/015359 describes electricity generators arranged on a wind turbine rotor blade assembly for electrically powering means for altering the pitch of the blades of the rotor blade assembly, each generator having a rotary portion co-operating with a ring gear of the nacelle of the rotor blade assembly.
It can be observed that some of the preceding documents relate, in particular, to aircraft that might fly through clouds full of supercooled water droplets, and that are continually being faced with the problem of icing. It can therefore be advantageous to arrange a power supply device permanently inside the propeller of such an aircraft for de-icing or anti-icing purposes.
In the same way, a device making it possible to power electrical means for altering the pitch of a propeller may be present permanently on the propeller.
Conversely, some aircraft, and in particular rotorcraft, do not need such an electrical power supply device to be installed permanently.
And so there is known a device provided with an AC generator connected to a power de-icing unit. The power de-icing unit is, in particular, provided with an electrical rectifier and with a sequencer for powering a plurality of electrical cables in a predetermined sequence. In addition, for safety reasons, the power de-icing unit is duplicated.
The generator and the power de-icing unit are installed in a static frame of reference, namely in the airframe of a rotorcraft.
The device then includes a slip-ring assembly comprising a non-rotary portion and a rotary portion that are interconnected via a system of brushes rubbing on slip rings. For example, the non-rotary portion may have circular slip rings powered electrically via electrical cables coming from the power de-icing unit, the rotary portion having a brush traveling over said slip rings.
The non-rotary portion then powers a plurality of heater mats per blade of a rotor following the sequence programmed in the power de-icing unit for de-icing the blades or for preventing ice from forming on said blades, each mat being connected via an electrical cable to a brush of the rotary portion of the slip-ring assembly.
The slip-ring assembly may be arranged reversibly so as to be used during winter periods only or for particular missions.
However, the slip-ring assembly is very heavy and difficult to put in place, in particular due to the presence of a large number of slip rings and of electrical cables of large dimensions.
In addition, each brush of the slip-ring assembly rubbing against the corresponding slip ring tends to degrade the performance of said slip-ring assembly. Maintenance actions requiring the device to be removed must then be taken relatively often. Unfortunately, since the slip-ring assembly is sometimes difficult to access, the cost of the maintenance can be high and requires the rotorcraft to be taken out of service for a long period of time.
Finally, it can be noted that, since the power de-icing unit is installed in the airframe of the aircraft, said power de-icing unit can disturb the surrounding electrical equipment. In addition, the power de-icing unit has overall size that is non-negligible and that is detrimental.
Documents U.S. Pat. No. 3,002,718, GB 545 305, EP 1 267 474, and DE 203 06 735 are also known.